In theory, it depends. In practice, slamming on your brakes is the correct call 99% of the time. To a large extent that is because of the "competent driver" part. I'd expect 80%+ of drivers to consider themselves just that, whereas the truth is of course the opposite.

So, the correct advice is to say "brake, don't swerve", so that drivers internalize that their first thought and reaction in any emergency should be to brake. Teach them to actually brake—fully press on the pedal—while you're at it.

A slightly more nuanced advice would be "brake first, swerve as needed as a follow-up".

But I would never in good conscience be able to give anyone advice to swerve instead of braking.